Kelly Osbourne lost almost 50lbs during her stint on Dancing with the Stars in 2009, she’s successfully kept the weight off since then. You know who hasn’t? Christina Aguilera.

Christina shocked audiences when she showed up at a Michael Jackson tribute concert last week, stretching the limits of her spandex leotard. X-tina has put on a few, and as far as Kelly Osbourne is concerned that means open season.

The two have had a contentious relationship for years, with Christina calling Kelly fat repeatedly. Well now it’s Kelly’s turn, Osbourne took to E! Fashion Police to bash Aguilera, “She called me fat for years. I was never that fat…So you know what? F**k you! You’re fat too.”

Thems fighting words Christina, maybe it’s time to head back to that boxing ring of your Dirrty days and fight it out… just maybe skip the bikini this time.